The mainstream view among astronomers and physicists today is that the cosmos (i.e. everything in existence) came into being 14 billion years ago (give or take a billion years or so) in the "Big Bang", at which point all matter and energy in existence were condensed in a small volume, and that the cosmos has expanded ever since, and continues to expand at a rate quantified by Hubble's constant. In this theory, raw matter and energy coalesced into stars, galaxies, and larger scale structures in accordance with physical laws. All atoms which exist today, under this theory, are the product of nuclear reactions(mostly nuclear fusion) which gave rise to the current mix of elements (found in the Periodic Table of the Elements) which are found in the universe.
Some of the main evidence for this theory comes from:
- The apparent motion of distant objects in space away from us in all directions.
- The apparent age of the light received from the most distant stars.
- A large scale distribution of massive visible objects in the universe, which shows a pattern of strands of dense matter surrounding large voids, consistent with a big bang model of cosmos formation.
- A distribution of elements in the observed universe consistent with random nuclear generation of those elements according to a Big Bang model.
- The pattern of cosmic background radiation observed in the universe.
The Big Bang, because it posits the sudden creation of the universe at a particular point in time plays an important role in the debate over Teaching Evolution. On one hand, it rejects a young earth creationist view, favored by some Evangelical Christians who see Genesis as literally true. On the other hand, by establishing a "creation event" with mainstream science, the Big Bang is viewed by many religious people as a true creation event, which is referred to only metaphorically in Genesis and other creation myths.
Some cosmologists suggest that the Big Bang could be an event that repeats every time the universe empties and cools off. According to Sean Carroll, University of Chicago Assistant Professor in Physics and her graduate student Jenniufer Chen, the Big Bang may actually be one of many big bangs that happen normally in the natural evolution of the universe over incredibly vast time scales as the universe.
Physicists Say Big Bang Was "Nothing Special" Every step in scientific understanding is a step in the same direction, away from religious fantasy and ignorance and toward greater connectedness and understanding.